1. Field of the Invention
The present invention relates to a colored curable composition, a color filter and a method of producing a color filter, a solid-state image sensor and a liquid crystal display device.
2. Description of the Related Art
As a method of producing a color filter used in liquid crystal display devices (LCDs) or solid-state image sensors (CCD or CMOS image sensors), a pigment dispersion method has been widely known.
A pigment dispersion method is a method of producing a color filter by photolithography using a colored photosensitive composition in which a pigment is dispersed in various kinds of photosensitive composition. This method, in which patterning is performed by photolithography, is known to be suitable for producing large-sized, high-definition color filters with high positional accuracy. When producing color filters by a pigment dispersion method, a coating film is formed by applying a photosensitive composition on a glass support with a spin coater or a roll coater, exposing the coating film to light and developing the same to form color pixels. A color filter is thus obtained by repeating these processes a number of times according to the number of colors used in the color filter.
One exemplary colored photosensitive composition in which a pigment is used is a blue colored composition for color filters in which a phthalocyanine pigment is included, as described in Japanese Patent Application Laid-Open (JP-A) No. 2001-33616.
When producing display devices, such as liquid crystal display devices or solid-state image sensors, by forming a color filter using a pigment, a pigment having a small particle size is desired in view of improving contrast. Problems in contrast are caused by light scattering due to a pigment or rotation of the polarizing axis by double refraction or the like. When micronization of a pigment is not sufficient, light is scattered or absorbed by the pigment, whereby light transmissivity is decreased and contrast is lowered and, moreover, curing sensitivity at the time of pattern exposure may be decreased.
In particular, in the field of color filters for solid-state image sensors, in which even higher definition has been required in recent years, further improvements in resolution has been difficult in a conventional pigment dispersion system, i.e., there are problems in that unevenness in color may occur due to coarse pigment particles, and the like. As a result, a pigment dispersion system is not suitable for applications that require a highly fine pattern for solid-state image sensors with a pixel size of from 1.5 to 3.0 μm square.
In response to such circumstances, techniques in which a dye is used instead of a pigment have been proposed. However, dyes have problems such as light resistance and heat resistance being inferior compared with pigments, which may cause problems in performance of color filters. There is also a problem in that a dye may precipitate due to its low solubility with respect to a photosensitive composition, and poor stability with time in the form of a liquid formulation or a coating film.
In view of such problems, a colored curable composition has been proposed in which a dye including a dipyrromethene compound and a phthalocyanine dye are used in combination, the composition exhibiting superior storage stability and being capable of forming a color filter that exhibits a high light resistance (see, for example, JP-A No. 2008-292970).
Further, a colored curable composition, in which a dye and a pigment are combined, is known (see, for example, United States Patent Application Publication No. 2008/0171271).